There is a need for being able to determine the position of a mobile terminal within a wireless communication system as accurately as possible. One successful approach is based on a fingerprinting approach; Adaptive Enhanced Cell ID (AECID) fingerprinting. Some basics of such a method can be found in the published international patent application WO 2007/043915. The output positioning data from such a system is typically provided as an area defined by a polygon. In the 3GPP standards, there is a possibility to report such polygons using a polygon message IE.
However, in many applications, it is also of interest to not only determine the lateral position, but also the altitude of the mobile terminal. The addition of altitude information is important e.g. in metropolitan areas with tall buildings, where the cell planning may be 3 dimensional. Then emergency positioning would benefit significantly by an altitude providing positioning fallback method to A-GPS. In such a case, an area associated with a position of a mobile terminal easily can be expressed by a polygon enhanced with altitude information of the polygon corners. A problem is, however, that there are no standardized formats for handling such types of information.
Reporting of altitude of polygon corners has been addressed by non-standard compliant means in the published international patent application WO 2008/054271. However, such solution requires that the involved nodes on both sides of a communication are updated concerning such non-standard solutions, a procedure which is both expensive and time consuming.